Currently, a system (so-called an electric license plate system) is under development to transmit and receive various data between a radio communication module fixed on a vehicular license plate and outer apparatuses (road-side units) installed on sides of roads for a registration management of vehicles, a traffic control and the like.
As a method to fix the radio communication module on the license plate, JP-2001-119175-A discloses, for example, that a casing, which is for installing the radio communication module on the license plate, is fixed on the license plate by welding and the like, and the radio communication module is installed in the casing.
However, the installation constriction of the radio communication module according to JP-2001-119175-A has a relatively poor workability in fixing the radio communication module on the license plate. The installation construction requires works such as welding to fix the casing on the license plate. Further, when it is necessary to detach the radio communication module from the license plate for a data maintenance, repair of failure and so on, the radio communication module cannot be easily detached from the license plate, so that the installation construction includes an issue in a viewpoint of operation and popularization of the products.
Current vehicular license plate is provided with two installation holes to fix itself on a vehicle. The license plate is screw-fastened to the vehicle by bolts inserted into the installation holes.
It is considered to fix the radio communication module on the license plate with use of these bolts. However, in a case that the radio communication module is screw-fastened by a pair of the bolts, an installation member and the like hides a part of an indication face of the license plate. In another case that the radio communication module is screw-fastened by a single bolt, the radio communication module may rotatably slide and is not stably fixed on the license plate.